import { addClass, removeClass } from './dom.js';

function Transition() {
    return {
        beforeEnter(el) {
            addClass(el, 'collapse-transition');
            if (!el.dataset) el.dataset = {};

            el.dataset.oldPaddingTop = el.style.paddingTop;
            el.dataset.oldPaddingBottom = el.style.paddingBottom;
            el.style.height = '0';
            el.style.paddingTop = 0;
            el.style.paddingBottom = 0;
        },

        enter(el) {
            el.dataset.oldOverflow = el.style.overflow;
            if (el.scrollHeight !== 0) {
                el.style.height = el.scrollHeight + 'px';
                el.style.paddingTop = el.dataset.oldPaddingTop;
                el.style.paddingBottom = el.dataset.oldPaddingBottom;
            } else {
                el.style.height = '';
                el.style.paddingTop = el.dataset.oldPaddingTop;
                el.style.paddingBottom = el.dataset.oldPaddingBottom;
            }

            el.style.overflow = 'hidden';
        },

        afterEnter(el) {
            // for safari: remove class then reset height is necessary
            removeClass(el, 'collapse-transition');
            el.style.height = '';
            el.style.overflow = el.dataset.oldOverflow;
        },

        beforeLeave(el) {
            if (!el.dataset) el.dataset = {};
            el.dataset.oldPaddingTop = el.style.paddingTop;
            el.dataset.oldPaddingBottom = el.style.paddingBottom;
            el.dataset.oldOverflow = el.style.overflow;

            el.style.height = el.scrollHeight + 'px';
            el.style.overflow = 'hidden';
        },

        leave(el) {
            if (el.scrollHeight !== 0) {
                // for safari: add class after set height, or it will jump to zero height suddenly, weired
                addClass(el, 'collapse-transition');
                el.style.height = 0;
                el.style.paddingTop = 0;
                el.style.paddingBottom = 0;
            }
        },

        afterLeave(el) {
            removeClass(el, 'collapse-transition');
            el.style.height = '';
            el.style.overflow = el.dataset.oldOverflow;
            el.style.paddingTop = el.dataset.oldPaddingTop;
            el.style.paddingBottom = el.dataset.oldPaddingBottom;
        },
    };
}

export default {
    name: 'MxCollapseTransition',
    functional: true,
    render(h, { children }) {
        let transition = new Transition();
        const data = {
            on: transition,
        };
        return h('transition', data, children);
    },
};
